TRANSIENT INCREASE IN THE RISK OF BREAST-CANCER AFTER GIVING BIRTH
TRANSIENT INCREASE IN THE RISK OF BREAST-CANCER AFTER GIVING BIRTH
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DOI：
10.1056/nejm199407073310102
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发表时间：
1994-07-07
影响因子：
158.5
通讯作者：
ADAMI, HO
中科院分区：
文献类型：
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作者：
LAMBE, M;HSIEH, CC;ADAMI, HO
背景。怀孕对乳腺癌风险的影响尚不清楚。我们检验了这样的假设：怀孕后患乳腺癌的风险会短暂增加，但随后会降至低于年龄匹配的未生育女性的水平。方法。我们利用癌症登记处和生育登记处之间的计算机化记录链接，对瑞典全国队列进行了病例对照研究。研究;受试者是 1925 年至 1960 年出生的女性，在 1960 年人口普查时她们是瑞典居民。共有 12,666 名乳腺癌患者与 62,121 名年龄匹配的对照受试者进行了比较。我们根据首次分娩时的母亲年龄（单产女性与未生育女性相比）和第二次分娩时的年龄（双产女性与单产女性相比），使用条件逻辑回归来估计不同年龄发生乳腺癌的比值比。结果。产后 15 年内，单产女性比未生育女性的乳房切除风险更高，此后风险更低。超额风险在第一次分娩时年龄较大的女性中最为明显（首次分娩时年龄为 35 岁的女性在分娩后 5 年的比值比为 1.26；95% 置信区间为 1.10 至 1.44）。两次怀孕的女性的风险增加不那么显着。结论。怀孕对患乳腺癌的风险有双重影响：它会暂时增加分娩后的风险，但会降低以后的风险。对于两次怀孕的女性来说，第一次怀孕所提供的长期保护掩盖了短期不良影响。一种看似合理的生物学解释是，怀孕通过刺激已经历恶性转化早期阶段的细胞的生长，增加了乳舞症的短期风险，但它通过诱导具有肿瘤变化潜力的正常乳腺干细胞的分化，提供了长期保护。
Background. The effect of pregnancy on the risk of breast cancer is not clear. We tested the hypothesis that the risk of breast cancer increases transiently after pregnancy but then falls to a level below that of age-matched nulliparous women.Methods. We conducted a case-control study of a nationwide cohort in Sweden, using a computerized record linkage between the Cancer Registry and the Fertility Registry. The study; subjects were women born from 1925 through 1960 who were resident citizens of Sweden at the time of the 1960 census. A total of 12,666 patients with breast cancer were compared with 62,121 age-matched control subjects. We used conditional logistic regression to estimate odds ratios for the development of breast cancer at different ages, according to maternal age at first delivery (in uniparous as compared with nulliparous women) and age at second delivery (in biparous as compared with uniparous women).Results. Uniparous women were at higher risk of breast cancel than nulliparous women for up to 15 years after childbirth and at lower risk thereafter. The excess risk was most pronounced among women who were older at the time of their first delivery (odds ratio 5 years after delivery among women 35 years old at first delivery, 1.26; 95 percent confidence interval, 1.10 to 1.44). Women who had two pregnancies had a less striking increase in risk.Conclusions. Pregnancy has a dual effect on the risk of breast cancer: it transiently increases the risk after childbirth but reduces the risk in later years. In women with two pregnancies, the short-term adverse effect is masked by the long-term protection imparted by the first pregnancy. A plausible biologic interpretation is that pregnancy increases the short-term risk of breast dancer by stimulating the growth of cells that have undergone the early stages of malignant transformation but that it confers longterm protection by inducing the differentiation of normal mammary stem cells that have the potential for neoplastic change.